One senior local government figure said his appointment suggests there were no 'big-hitters' interested in the top job at the troubled COSLA.
He said: 'He is a former chief executive so they have managed to attract a fairly good calibre of applicant. But I think that if a really heavyweight chief executive had gone for it, they would have got it.'
Mr Mair was up against some tough competition, however, including Clackmannanshire chief executive Keir Bloomer and South Ayrshire Council's social work director Elaine Noad.
Following re-organisation in 1996, he was appointed corporate manager of social strategy in Fife. He worked with Highlands & Islands Enterprise until his contract ended last year and he took the job at East Renfrewshire Council.
East Renfrewshire's chief executive Peter Daniels said: 'I am carrying out restructuring so Mr Mair has been handling the sport and recreation services. He has done a great job and this is a cracking appointment for COSLA. Persuading the councils [which left] back into the organisation will be a priority.'
Mr Mair could make or break his return to the local government major league by persuading the three authorities back into the organisation. There is no indication Clackmannanshire, Falkirk, and Glasgow City councils have plans to rejoin COSLA. All have agreed their budget and council tax for the coming year, so the earliest they are likely to rejoin is 2003.
COSLA president Pat Watters (Lab) said: 'Last year was one of the most difficult in COSLA's history. We are all fully committed to leading COSLA forward into a new era campaigning for local government and promoting its collective agenda.'
Mr Mair said he was 'delighted' to be appointed.
What they were saying about Rory Mair's appointment
'There was very little interest in the job among the higher levels of local government, but Mr Mair could start to put things back on track.'
'He missed getting a job he wanted in the reorganisation and has been in stop-gap jobs since then. No-one really knows how effective he'll be at COSLA.'
'This suggests there were no heavyweight contenders for
'This is a good appointment, but he'll have to try to persuade the three councils to rejoin. COSLA is poorer without them.'
'Rory Mair has an excellent track record.'
'Scotland needs a 32-member confederation and he needs to persuade the three back in.'